6 - (1,2,3,4 - tetrahydro - 2 - thioxo - 4,4,6-trimethyl - 1 - pyrimidinyl) - 2 - benzothiazolylthiocarbamates



United States Patent sazsama 6 (1,2,3,4 TETRAHYDRO 2 THIUXO 4,4,6

TRKMETHYL 1 PYRlMlDlNYL) 2 BEN- ZOTHIAZGLYLTTHOCARBAMATES John J.DArnico, Charleston, W. Va., and Ching C. Tong, Kirkwood, M0., assignorsto Monsanto Company, a corporation of Delaware No Drawing. Originalapplication Sept. 15, 1961, Ser. No. 138,296, now Patent No. 3,151,114,dated Sept. 29, 1964. Divided and this application Dec. 27, 1963, Ser.No. 334,024

9 Claims. (Cl. 260--247.1)

1 13:5 BIT-W s g osn l N s g [D CSH I N6 CH3 The structure isundoubtedly ll predominately. For example a disodium salt does not form.Of course, the same tautomerism is possible in the mercaptothiazolenucleus but the mercaptan structure is generally accepted and isconsistent with the chemical properties observed. The preparation andproperties of this compound are described in detail below:

and

Example 1 To a stirred slurry containing 79.0 grams (0.5 mole) of1,1-dimethyl-3-oxobutylthiocyanic acid, 750 ml. of water and 6 grams ofconcentrated sulfuric acid was added in one portion 91.1 grams (0.5mole) of 6-amino- Z-mercaptobenzothiazole and the mixture heated at 8090 C., for a period of 3 hours. After cooling to 25 C., the precipitateWas collected by filtration, washed with water until the washings wereneutral to litmus and airdried at 2530 C.1,4-dihydro-l-(2-mercapto-6-benzothiazolyl)-4,4,6-trimethylZ-pyrimidinethiol (predominately 1,2,3,4-tetrahydro1-(Z-mercapto-6-benzothiazolyl)-2-thioxo-4,4,e-trimethylpyrimidine) wasobtained in 97.5% yield. After recrystallization from dilute ethylalcohol it melted at 207209 C. Analysis gave 13.07% nitrogen and 29.34%sulfur compared to 13.07% nitrogen and 29.72% sulfur calculated for CI-1 N 8 This compound accelerates vulcanization of natural and syntheticrubber and imparts considerable processing safety. It is also a valuableintermediate and undergoes reactions typical of those known formercaptobenzothiazole involving the mercaptan radical.

Since the mercapto hydrogen in the thiazole ring is active, a variety ofderivatives can be obtained by re- Patented Dec. Ell, l965 placing thehydrogen by other groops, as for example salt-forming groups and organicradicals. Among the organic radicals which may replace hydrogen arealkyl, alkenyl, halogen substituted alkenyl, dialkylaminoethyl,Z-butenylene, 2-butynyl, 2'propynyl, 2cyclohexenyl, 2- oxocyclohexyl,5,5,7,7-tetramethyl-2-octenyl,

where X is sulfur or oxygen and the valences on the nitrogen may besatisfied by open or closed chain aliphatic radicals or divalentradicals which with nitrogen constitute a heterocyclic group, or phenyl,

(lfX-Y groups where X is sulfur or oxygen and Y is lower alkyl oralkenyl,

i i i O (JOCI-IzOH2-OCH CH2OU-, -UOGH CH O CH COOH, andchlorophenoxyacetyl. These, of course, are only illustrative of a few ofthe possible derivatives. All of them accelerate vulcanization to agreater or less degree. Replacing mercapto hydrogen with radicals whichinactivate mercaptobenzothiazole do not appear to have the same effecton the product of Example 1. The term free mercaptan hereafterdesignates the product of Example 1.

Example 2 A solution containing 32.2 grams (0.1 mole) of free mercaptan,6.3 grams (0.1 mole) of potassium hydroxide, 500 ml. of acetone and 10ml. of water was heated to 56 C. While stirring the resultant solutionat 25 C. there was added in one portion 10.8 grams (0.1 mole) ofdimethylcarbamyl chloride. The reaction mixture was stirred at 25-30 C.for 5 /2 hours and then added to 1000 grams of ice-water. Stirring wascontinued at 0-10 C. for 30 minutes. The percipitate was collected byfiltration, washed with water until the washings were neutral to litmusand air-dried at 25-30 C. 6-(l,2,3, 4 tetrahydro 2thioxo-4,4,6-trimethyl-l-pyrimidinyl)-2-benzothiazolyldimethylthiolcarbamate was obtained in 61.4% yield as a tan solidmelting at l96-l98 C. after recrystallization from ethyl alcohol/acetonemixture. Analysis gave 13.70% nitrogen and 24.99% sulfur compared to14.27% nitrogen and 24.51% sulfur calculated for C H N OS Employing thesame procedure and substituting the appropriate halide, other productsprepared were:

No. 3. 6-(1,2,3,4-tetrahydro-2-thioxo-4,4,6-trimethyl- 1-pyrimidinyl)-2benzothiazolyl N ethyldithiocarbanilate in 97.5% yield fromN-ethylphenylthiocarbamyl chloride. The reaction mixture was stirred at25--30= C. for 24 hours. The product was a tan solid melting at 173-175C. after recrystallization from dilute acetone. Analysis gave 10.82%nitrogen compared to 11.56% calculated for C l-l N S No. 4. 6(1,2,3,4-tetrahydro-2-thioxo-4,4,6-trimethyl- 1-pyrimidinyl)-2benzothiazolyl l pyrrolidinecarbothiolate in 52.5% yield froml-tpyrrolidinecarbamyl chloride. The reaction mixture was stirred at2530 C. for 5 /2 hours. The product was a yellow-green solid melting atMil-183 C. after recrystallization from dilute acetone. Analysis gave12.96% nitrogen compared to 13.39% calculated from C H N OS No. 5. 6(1,2,3,4tetrahydro-2-thioxo-4,4,-trimethyll-pyrimidinyl)-2-benzothiazolyl1 pyrrolidinecarbodithioate in 11.5% yield froml-pyrrolidinethiocarbamyl chloride. The reaction mixture was stirred at2530 C. for 24 hours. The product was a tan solid melting at 218 220 C.with decomposition. Analysis gave 12.16% nitrogen compared to 12.89%calculated for C I-1 N 5 No. 6. 6(1,2,3,4-tetrahydro-2-thioxo-4,4,6-trimethyl- 1pyrimidinyl)-2benzothiazolyl 1 piperidinecarbodithioate in 89.4% yield frompiperidinethiocarbamyl chloride. The reaction mixture was stirred at25-30 C. for 24 hours. The product was a tan solid melting at 151- 153C. after recrystallization from alcohol/chloroform. Analysis gave 11.93%nitrogen and 28.44% sulfur compared to 12.49% nitrogen and 28.59% sulfurcalculated for CZUHZ4N4S4.

No. 7. 6(1,2,3,4-tetrahydro-2-thioxo-4,4,6-trimethyll-pyrimidinyl)-2-be11zothiazolyl-2,6-dimethylmorpholinocarbodithioatein 41.9% yield from 2,6-dimethylmorpholinethiocarbamyl chloride. Asemi-solid resulted after adding 1000 grams of ice-water and stirring at10 C. for an hour. To this semi-solid was added 500 ml. of ethyl etherand stirring was continued at 010 C. for another thirty minutes. Aprecipitate then formed which was isolated as hereinbefore described.The product was a tan solid melting at l73174 C. after recrystallizationfrom dilute acetone. Analysis gave 11.89% nitrogen and 26.25% sulfurcompared to 11.70% nitrogen and 26.78% sulfur calculated for C H N OS Inthe following preparations the solution was made up of 32.2 grams (0.1mole) of free Inercaptan, 500 ml. of acetone and 6.6 grams (0.1 mole) of85% potassium hydroxide:

No. 8. 6 (1,2,3,4-tetrahydro-2-thioxo4,4,6-triemthyl- 1-pyrimidinyl)-2benzothiazolyl diethyldithiocarbamate in 96.5% yield fromdiethylthiocarbamyl chloride dissolved in 100 .ml. of acetone. Thestirred reaction mixture was maintained at 25-30 C. for /2 hours. Theproduct was a tan solid melting at 227 C. after recrystallization fromchloroform and ethyl acetate. Analysis gave 12.30% nitrogen compared to12.83% calculated for C19H24N4S4- No. 9. 6(1,2,3,4-tetrahydro-2-thioxo-4,4,6-trimethyll-pyrirnidinyl)-2-benzothiazolyldimethyldithiocarbamate in 61.3% yield from dimethylthiocarbamylchloride dissolved in 100 ml. of acetone. The product was a tan solidmelting at 213215 C. after recrystallization from chloroform and ethylalcohol. Analysis gave 13.98% nitrogen compared to 13.71% calculated forC I-1 N 5 No. 10.6-(1,2,3,4-tetrahydro-2-thioxo-4,4,6-trimethyll-pyrimidinyl) 2benzothiazolyl morpholinecarbodithioate in 97.5% yield frommorpholinethiocarbamyl chloride. The product was a tan solid melting atl99201 C. after recrystallization from chloroform and ether. Anal ysisgave 12.25% nitrogen compared to 12.43% calculated for c gHizgNi os No.11. 6-(1,2,3,4-tetrahydro-2-thioxo-4,4,G-trimethyl- 1 pyrimidinyl) 2benzothiazolyl diisopropyldithiocarbamate in 88.2% yield fromdiisopropylthiocarbamyl chloride. The product was a tan solid melting at197- 199 C. after recrystallization from chloroform and ether. Analysisgave 12.27% nitrogen and 27.36% sulfur compared to 12.06% nitrogen and27.60% sulfur calculated for C21H23N4S4.

No. 12. 6-(1,2,3,4tetrahydro-2thioxo-4,4,6-trimethyl- 1pyrimidinyl)-2benzothiazolyl dibutyldithiocarbamate in 99.5% yield fromdibutylthiocarbaniyl chloride. The product was a tan solid melting at180482 C. after recrystallization from chloroform and ether. Analysisgave 25.82% sulfur compared to 26.03% calculated for 2s 32 4 4- No. 13.6-(1,2,3,4-tetrahydro-2-thioxo-4,4,6-trimethyll-pyrimidinyl)-2-benzothiazolyldiethylthiolcarbamate in 76.0% yield from diethylcarbamyl chloride. Theproduct was a tan solid melting at 144-146 C. Analysis gave 13.39%nitrogen and 23.08% sulfur compared to 13.32%

nitrogen and 22.87% sulfur calculated for C 1-I N OS No. 14. 6-(1,2,3,4'tetrahyd-ro-2-thioxo-4,4,6-trimethyll-pyrimiclinyl -2-benzothiazolyldipropyldithiocarbamate in 54.0% yield from dipropylthiocarbamylchloride. The

5 product was a tan solid melting at 185187 C. after recrystallizationfrom chloroform and ether. Analysis gave 12.12% nitrogen and 26.95%sulfur compared to 12.06% nitrogen and 27.60% sulfur calculated for C HN S As further illustrative of the invention, natural rubber A. 6(1,2,3,4 tetrahydro 2 thioxo 4,4,6trimethyl-l-pyrimidinyl)-2-benzothiazolyl dimethylthiolcarbamate B. 6(1,2,3,4 tetrahydro 2 thioxo 4,4,6 tri- 30methyl-l-pyrimidinyl)-2-benzothiazolyl N ethyldithiocarbanilate C. 6(1,2,3,4 tetrahydro 2 thioxo 4,4,6 trimethyl- 1 -pyrimidinyl)-2-benzothiazolyl l-pyrrolidinecarbothiolate D. 6 (1,2,3,4 tetrahydro 2thioxo 4,4,6 trimethyl-l-pyrimidinyl)-2-benzothiazolyll-pyrrolidinecarbodithioate E. 6 (1,2,3,4 tetrahydro 2 thioxo 4,4,6trimethyl-l-pyrimidinyl)-2 benzothiazolyl l-piperidinecarbodithioate F.6 (1,2,3,4 tetrahydro 2 thioxo 4,4,6 trimethyl 1 pyrimidinyl) 2benzothiazolyl 2,6- dimethylmorpholinocarbodithioate The stocks Werecured in the usual manner by heating in a press for different periods oftime at 144 C. Processing safety of the vulcanizable stocks wasevaluated by means of a Mooney plastometer. The figures recorded Werethe times required for the Mooney plasticity at 135 C. to rise tenpoints above the minimum value.

The modulus and tensile properties of the minute cures are recorded:

TABLE I Modulus of 55 Elasticity in Tensile at Mooney Scorch Stocklbs/in. at Break in at 135 C.

Elongation of lbs/in.

A 1, 250 2, 150 12. 8 1, 880 3,000 13. 6 1, 170 2, 240 ll. 5 1, 500 2,050 12. 4 1, 950 2, 980 12. 7 1, 710 3,060 13. 3

As further examples of the invention rubber base stocks Were preparedcomprising:

Parts by Weight Smoked sheets rubber 100.0 Carbon black 50.0 Zinc oxide5.0 Stearic acid 3.0 Saturated hydrocarbon softener 3.0 Antioxidant 1 .5Sulfur 2.5 Accelerator 0.5

Accelerators added to the base stock were:

Stock:

G. 6- 1,2,3,4-tetrahydro-2-thioxo-4,4,6-trimethyl-1-pyrimidinyl)-2benzothiazolyl diethyldithio carmate H.6-(1,2,3,4-tetrahydro-2-thioxo-4,4,G-trimethyl-lpyrimidinyl)-2-benzothiazolyldimethyldithiocarbamate I. 6- 1,2,3,4-tetrahydro-2-thioxo-4,4,6-trimethy1-1- pyrimidinyl)-2-benzothiazolylmorpholinecarbodithioate K.6-(1,2,3,4-tetrahydro-2-thioxo-4,4,6-trimethyl-1-pyrimidinyl)-2-benzothiazo1y1 diisopropyldithiocarbamate L. 6- 1,2,3,4-tetrahydro-2-thioX0-4,4,6-trimethyl-1- pyrimidinyl)-2-benzothiazolyldibutyldithiocarbamate M.6-(1,2,3,4-tetrahydro-2-thioxo-4,4,6-trimethyl-1-pyrirnidinyl)-2-benzothiazolyl diethylthiolcarbamate N.6-(1,2,3,4-tetrahydro-2-thioxo-4,4,6-trimethyl-1-pyrimidinyl)-2-benzothiazoly1 dipropyldithiocarbamate The compositionswere vulcanized by heating for diiferent periods of time in the usualmanner in a press at 144 C. The accelerating properties of the 15 minutecures and processing safety are recorded in Table II.

It is intended to cover all changes and modifications of the examples ofthe invention herein chosen for purposes of disclosure which do notconstitute departures from the spirit and scope of the invention.

What is claimed is:

1. A compound of the formula where T is6-(1,2,3,4-tetrahydro-2-thioXo-4,4,G-trimethyll-pyrimidinyl)-2-benzothiazoly1,X is selected from a group consisting of oxygen and sulfur, R isselected from a group consisting of lower alkyl and phenyl, R is loweralkyl and R and R taken together and with the nitrogen attached theretoconstitute a heterocyclic radical selected from the group consisting ofl-pyrrodinyl, piperidino, morpholino, and dimethylmorpholino.

2. 6-( l,2,3,4-tetrahydro 2-thioxo4,4,6-trimethyl-1-pyrimidinyl)-2-benzothiazolylN-ethyldithiocarbanilate.

3. 6-( l,2,3,4-tetrahydro-2-thioxo4,4,6-trimethyl-1-pyrimidinyl)-2-benzothiazolyl1-piperidinecarbodithioate.

4. 6-(1,2,3,4-tetrahydro-2-thioxo 4,4,6-trimethyl-l-pyrimidinyl)Z-benzothiazolyl 2,6-dimethylmorpholinecarbodithioate.

5. 6-(1,2,3,4-tetrahydro-Z-thioxo4,4,6-trimethyl-1-pyrimidinyl)-2-benzothiazolyl diethyldithiocarbamate.

6. 6-( l,2,3,4-tetrahydro-2-thioxo4,4,6-trimethyl-l-pyrimidinyl)-2-benzothiazo1yl dibutyldithiocarbamate.

7. 6-(1,2,3,4-tetrahydro-2-thioxo4,4,6-trimethyl-1-pyrimidinyl)-2-benzothiazolyl dipropyldithiocarbamate.

8. 6-(1,2,3,4-tetrahydro-2-thiox04,4,6-trimethyl-1-pyrimidinyl)-2-benzothiazolyl dimethyldithiocarbamate.

9. 6-(1,2,3,4-tetrahydro-2-thioxo4,4,6-trimethyl-1-pyrirnidinyl)-2-benzothiaz0ly1 diethylthiolcarbamate.

No references cited.

IRVING MARCUS, Primary Examiner.

NICHOLAS S. RIZZO, Examiner.

1. A COMPOUND OF THE FORMULA